ADP-ribosylation of actin from the green algaChara corallina byClostridium botulinum C2 toxin andClostridium perfringens iota toxin

Summary The ability of two bacterial toxins to modify a plant actin by covalent ADP-ribosylation was tested in the green algaChara corallina. Using [³²P]NAD, bothClostridium botulinum C2 toxin andClostridium perfringens iota toxin labelled a protein of M_r 42 kDa which comigrated with actin and was immunoprecipitated by a monoclonal anti-actin antibody. ADP-ribosylation ofChara actin was more efficient with iota toxin than with C2 toxin. The actin bundles in perfusedChara cells were not affected by toxin-containing media competent for ADP-ribosylation. The data indicate that monomeric plant actin is substrate for ADP-ribosylation by the bacterial toxins.Abbreviations ADP adenosine-diphosphate - EGTA ethyleneglycol-bis-(-aminoethyl)N,N,N,N-tetraacetic acid - NAD nicotinamide dinucleotide - pCA -log [Ca²⁺] - PIPES piperazine-N,N-bis(2-ethanesulfonic acid)Dedicated to Prof. Dr. Dr. h.c. Eberhard Schnepf on the occasion of his retirement